1. Field of the Invention
This invention relates to a dye-forming charge-sensitive recording element and process. One aspect of the invention relates to the use of a vinyl addition polymer in the electrically active conductive layer, referred to herein as a polymeric EAC layer, in a charge-sensitive recording element which is capable of producing a dye image and silver image by dry development processes.
2. Description of the State of the Art
Production of a dye image and silver image in an electrically activatable recording material by dry development techniques is described in copending U.S. application Ser. No. 055,945, of M. Lelental, filed July 9, 1979, titled "Dye Forming Electrically Activated Recording Material and Process", now abandoned and commonly assigned with the present application to Eastman Kodak Company, and Research Disclosure, October 1979, Item 18627. In accordance with that invention, production of a dye image and silver image is accomplished by means of an electrically activated recording element comprising an electrically conductive support, such as a poly(ethylene terephthalate) film having a cermet coating on the film, having thereon, in sequence, (a) an electrically activated recording layer comprising an organic silver salt and a reducing agent, and (b) a photoconductive layer separated from (a) by an air gap of up to 20 microns and (c) an electrically conductive layer on (b), wherein the recording layer comprises, in reactive association, (A) a dye-forming coupler, and (B) an oxidation-reduction combination comprising (i) an organic silver salt oxidizing agent, with (ii) a reducing agent which, in its oxidized form, forms a dye with the dye-forming coupler. Such an electrically activated recording element enables formation of a dye image and silver image by heat processing after imagewise exposure. It has been desirable to increase the charge sensitivity of such elements. Increased charge sensitivity would lower the levels of charge required to form a latent image in the electrically activated recording layer.
In our attempt to increase charge sensitivity, we found that a polymeric layer between the electrically conductive support and the electrically activated recording layer could provide some increased charge sensitivity. However, as indicated in the following comparative examples, many polymeric materials do not provide a suitable increase in charge sensitivity. No answer to the problem of producing the desired degree of increased charge sensitivity by means of some type of interlayer or some type of polymer in a subbing layer was clear from the art.